|Miller, William - Bill|
Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/13/2007
Publication Date: 3/1/2007
Citation: Stoddard, R.A., Miller, W.G., Foley, J.E., Lawrence, J., Gullard, F.M., Conrad, P.A., Byrne, B.A. 2007. Campylobacter insulaenigrae isolated from northern elephant seals (mirounga angustirostris) in california. Applied and Environmental Microbiology. 7(6)1729-1735 Interpretive Summary: Recently, a novel bacterium, Campylobacter insulaenigrae, a relative of the human bacterial pathogen Campylobacter jejuni was isolated from seals and porpoises in Scotland. This study describes the isolation of C. insulaenigrae from multiple elephant seals in California, both free-ranging seals and seals undergoing rehabilitation at the Marine Mammal Center of Sausalito, California, following stranding on beaches throughout northern California. A novel typing method was developed to distinguish between different strains of this species. Using this new typing method, the majority of California strains were found to be distinct from the original Scottish strains, although “Scottish-like” strains were found in California to some extent towards the end of the study. Typing also showed a close relation between C. insulaenigrae and C. lari, a common pathogen found in the marine environment, that often contaminates shellfish. Identification of this species was not possible using typical biochemical tests and assays, indicating that a more molecular approach is needed for exact identification.
Technical Abstract: There are only two reports in the literature demonstrating the presence of Campylobacter spp. in marine mammals. One report describes the isolation of a new species, Campylobacter insulaenigrae sp. nov, from three harbor seals (Phoca vitulina) and a harbor porpoise (Phocoena phocoena) in Scotland and the other described the isolation of Campylobacter jejuni, C. lari and an unknown Campylobacter species from northern elephant seals (Mirounga angustirostris) in California. In this study, 72 presumptive C. lari and unknown Campylobacter species strains were characterized using standard phenotypic methods, 16S rRNA PCR, and multilocus sequence typing (MLST). Phenotypic characterization of these isolates showed them to be variable in their ability to grow either at 42°C or on agar containing 1% glycine, and their sensitivity to nalidixic acid and cephalothin. Based on both 16S rRNA PCR and MLST, all but one of the 72 isolates were found to be C. insulaenigrae, with one isolate being similar to, but distinct from, both C. upsaliensis and C. helveticus. Phylogenetic analysis identified two C. insulaenigrae clades: the primary clade containing exclusively California strains and a secondary clade containing some California strains and all of the original Scottish strains. This study demonstrated the inability of phenotypic characterization to correctly identify all Campylobacter species and emphasizes the importance of molecular characterization via 16S rRNA sequence analysis or multiplex PCR, for the identification of Campylobacter isolates from marine mammals.